Controlling a temperature of a window covering an etching chamber where a plasma processing process (e.g., a plasma etching process) is performed is an important issue associated with thermal stress and processing distribution within the window. In addition, the thermal stress and the processing distribution are issues affecting the yield.
In general, in the window of the etching chamber where a plasma processing process is performed, a higher temperature may be sensed at its center, compared to its edge. In order to appropriately control the thermal stress and the processing distribution within the window of the etching chamber, it may be important to reduce a temperature difference between the center and the edge of the window. Accordingly, there are increasing demands for research into methods for reducing the temperature difference.